PROJECT SUMMARY AND ABSTRACT The World Health Organization calls on all countries to reduce sugar intake among children because of the solid evidence that limiting intake of free (added) sugars reduces the risks of obesity, tooth decay, and later heart disease. In the United States, preschoolers are consuming, often in the context of snacking, approximately 13 teaspoons of added sugars daily, more than double what the American Heart Association recommends for children. Evidence-based strategies to effectively reduce added sugar intake and promote the liking of beverages and foods containing less added sugar are a clear public health priority. Our proposed randomized controlled trial builds upon our prior NIH-sponsored research that demonstrates the plasticity of preferences during early life and the fundamental role that repeated exposure has on shifting preferences. We have established that children have inborn, elevated preferences for sweet taste, that sugary snacks are often offered for nonnutritive reasons by mothers, and that personal variation in the reward sensitivity and appetitive tastes may make some children more susceptible to dietary excess of sugars from snacks. This proposed research will be the first randomized controlled trial to determine whether sweet preferences can be downshifted in preschoolers by a 4-month exposure to daily snacks containing reduced levels of added sugars and sweetness (intervention group) compared to a similarly aged control group whose daily snacks will be more than twofold higher in total sugar and fivefold higher in added sugar (Specific Aim 1). We will also determine whether the impact of the intervention generalizes to other foods as reflected by greater liking and intake of novel low-sugar snacks in the laboratory and by lower free- living intake of added sugars, validated by biomarkers of cane and corn sugar, the two predominant added sugars in the US food supply (Specific Aim 2). We will further examine whether inter-individual variation in taste genotype, appetitive regulation traits, and reward sensitivity determines whether certain children are less successful in shifting preference than others (Specific Aim 3). The Secondary Aim will explore the trickle-down effects of the intervention on mothers by examining the extent to which their sweet preferences are affected by feeding their children snacks with lower levels of sugar and sweetness. To accomplish our goals, we have assembled a multi-institutional, interdisciplinary team of investigators, each of whom brings unique and necessary expertise in human taste perception and genetics, child appetite regulation, biomarkers, pediatric dentistry, and statistical methods. Findings will provide new insight on family-based, personalized approaches for increasing young children?s liking of foods lower in added sugar and sweetness. This research will serve the long-term goals of establishing evidenced-based strategies to reduce children?s consumption of added sugar and promoting healthy snacking behaviors.